Final answer:
Dolphins and seals have flipper bones that are considered homologous structures, indicating a common ancestor and divergent evolution adapting their limbs to different environments.
Step-by-step explanation:
The flipper bones in dolphins and seals are homologous structures.
It is because dolphins and seals, along with humans, cats, and whales, are all mammals and share a common ancestor. Their limb bones have similar arrangements despite different shapes and sizes, and these adaptations occurred due to their respective environments and lifestyles.
We see a difference in the shape and proportion of the limbs within these species due to the process called divergent evolution, where genetically similar structures adapt to different functions.